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An h-adaptive numerical manifold method for solid mechanics problems

Science China(Technological Sciences) 2018年第6期61卷 923-933页

作者： YU ChangYi LIU feng XU ying State Key Laboratory of Hydraulic Engineering Simulation and Safety School of Civil Engineering Tianjin University Tianjin 300072 China State Key Laboratory of Geomechanies and Geoteehnical Engineering Institute of Rock andSoil Mechanics Chinese Academy of Sciences Wuhan 430071 China

The numerical manifold method(NMM) features its dual cover systems, namely the mathematical cover and physical cover,which provide a unified framework for mechanics problems involving continuum and discontinuum deformation. Uniform finite element meshes can be and are usually used to construct the mathematical cover. Though this strategy can handle different kinds of problems in a unified way, it is not economical for cases with steep deformation gradients or singularities. In this paper, using the recovery-based error estimator, an h-adaptive NMM on quadtree meshes is proposed to deal with such cases. The quadtree meshes serve as the mathematical meshes, on which the local refinement is carried out. When the quadtree meshes are refined,the corresponding mathematical cover, physical cover and manifold elements are updated accordingly. To handle the hanging nodes in the quadtree meshes, we resort to mean value coordinates. Comparing to the refinement based on manifold elements,the proposed strategy guarantees consistent structured meshes throughout the adaptive process, thus retaining the unique feature of original NMM. In contrast with polygonal finite element method, an advantage of the proposed method is that the meshes do not need to conform to the crack face and material boundary, which means the adaptive NMM is very suitable for problems with complex geometric boundary. Several representative mechanics problems, including crack problems, are analyzed to investigate the effectiveness of the proposed method. It is demonstrated that the proposed adaptive NMM has higher accuracy and better performance comparing to uniform refinement strategy.

关键词： numerical manifold method (NMM) adaptive analysis quadtree meshes mean value coordinates cover refinement

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Perfect State Transfer on Weighted Abelian Cayley Graphs

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Chinese Annals of Mathematics,Series B 2021年第4期42卷 625-642页

作者： Xiwang CAO Keqin feng ying-ying TAN Department of Mathematics Nanjing University of Aeronautics and Astronau-ticsNanjing 210016China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China School of Mathematics and Physics Anhui Jianzhu UniversityHefei 230601China

Recently,there are extensive studies on perfect state transfer(PST for short)on graphs due to their significant applications in quantum information processing and quantum ***,there is not any general characterization of graphs that have PST in *** this paper,the authors present a depiction on weighted abelian Cayley graphs having *** give a unified approach to describe the periodicity and the existence of PST on some specific graphs.

关键词： Perfect state transfer Cayley graph Eigenvalues of a graph Weighted graph Random walk

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Relationship Between the Formation of Clusters in Electrorheological Fluids and Their Fractal Dimension

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Chinese Physics Letters 1995年第8期12卷 501-504页

作者： WU feng TANG Xinlu YANG Yuegui WANG xiaohong Department of Modern Mechanics University of Science and Technology of ChinaHefei 230026

In this paper,the scaling properties of aggregation of particles in electrorheological fluids(ERF)are *** is found that the cluster size is related to both the space dimension and its fractal dimension,*** structure of *** analyzing the experimental data and the results of computer simulations we have shown that the fractal dimension of the particle clusters in ERF is one for 2-dimensional space and 5/4 for 3-dimensional space.

关键词： cluster. space. dimension

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Stimuli-Responsive Interconversion between Poly-NHC-Based Organometallic Assemblies and Their Self-Aggregated Dimers

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Chinese Journal of Chemistry 2024年第22期42卷 2840-2844页

作者： Guang-feng Jin ying-feng Han Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education Xi'an Key Laboratory of Functional Supramolecular Structureand MaterialsCollege of Chemistry and Materials ScienceNorthwest UniversityXi'anShaanxi 710127China

Comprehensive Summary Poly-NHC-based organometallic assemblies 3-PF6,3-SbF6 and 3-OTf were obtained and verified by NMR spectroscopy,ESI mass spectrometry and single-crystal X-ray diffraction *** structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration,solvent and metal ion.1H NMR spectra of assembly 3-PF6 in CD3CN at different concentrations demonstrated controllable structural interconversion,and 19F NMR spectrum of assembly 3-PF6 at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of *** addition,single-crystal X-ray diffraction analysis provided clear evidence that in the solid state,two assemblies 3-PF6 were vertically stuck,forming a self-aggregated dimer with an encapsulated hexafluorophosphate *** the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.

关键词： N-Heterocyclic carbene Organometallic assemblies Self-aggregated dimer Stimuli-responsive Structural interconversion Concentrationl Solvent Metalion

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Morphologies evolution and mechanical behaviors of SiC nanowires reinforced C/(PyC-SiC)_(n)multilayered matrix composites

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Journal of Materials Science & Technology 2022年第1期96卷 190-198页

作者： Xinfa Tian Hejun Li xiaohong Shi Hongjiao Lin Ningning Yan Tao feng State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research CenterNorthwestern Polytechnical UniversityXi’an 710072China School of Mechanics Civil Engineering&ArchitectureNorthwestern Polytechnical UniversityXi’an 710072China

SiC nanowires reinforced C/(PyC-SiC)_(n)multilayered matrix composites(SM-CS for short)were prepared by combined with sol-gel and chemical vapor infiltration(CVI)***,(PyC-Si OC);multilayered structure was formed by cycles of impregnation and *** SiOC was transformed into SiC by heat-treatment,and(PyC-SiC)_(n)multilayered structure would be *** the same time,the PyC layer which was designed as the outmost layer could decrease gas supersaturation to form in-situ tubular SiC nanowires on the surface of multilayered *** results of three-point bending test showed that the maximum force of SM-CS composites was increased by the number of cycles of the preparation process,which were up to enhanced by 74.38%compared with C/C composite *** fracture surface showed that the improvement was due to the multiscale reinforcing system of(PyC-SiC)_(n)multilayered structure and SiC *** structure can protect carbon fibers and release stress concentration by induction of *** the mechanical interlocking effect of SiC nanowires could reinforce bonding force of the remaining matrix.

关键词： C/C Multilayered structure SiC nanowires Flexural property

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An improved GNSS ambiguity best integer equivariant estimation method with Laplacian distribution for urban low-cost RTK positioning

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Satellite Navigation 2024年第1期5卷 109-124页

作者： ying Liu Wanke Liu xiaohong zhang Yantao Liang Xianlu Tao Liye Ma School of Geodesy and Geomatics Hubei Luojia LaboratoryWuhan University129 Luoyu RoadWuhan430079HubeiChina Chinese Antarctic Center of Surveying and Mapping Wuhan University129 Luoyu RoadWuhan430079HubeiChina School of Instrument Science and Engineering Southeast UniversityNanjingJiangsuChina The 54 Research Institute of China Electronics Technology Group CorporationShijiazhuang050081HebeiChina State Key Laboratory of Satellite Navigation System and Equipment Technology Shijiazhuang050081HebeiChina

The integer least squares(ILS)estimation is commonly used for carrier phase ambiguity resolution(AR).More recently,the best integer equivariant(BIE)estimation has also attracted an attention for complex application scenarios,which exhibits higher reliability by a weighted fusion of integer ***,traditional BIE estimation with Gaussian distribution(GBIE)faces challenges in fully utilizing the advantages of BIE for urban low-cost positioning,mainly due to the presence of outliers and unmodeled *** this end,an improved BIE estimation method with Laplacian distribution(LBIE)is proposed,and several key issues are discussed,including the weight function of LBIE,determination of the candidates included based on the OIA test,and derivation of the variance of LBIE solutions for reliability *** results show that the proposed LBIE method has the positioning accuracy similar to the BIE using multivariate t-distribution(TBIE),and significantly outperforms the ILS-PAR and GBIE *** an urban expressway test with a Huawei Mate40 smartphone,the LBIE method has positioning errors of less than 0.5 m in three directions and obtains over 50%improvements compared to the ILS-PAR and GBIE *** an urban canyon test with a low-cost receiver STA8100 produced by STMicroelectronics,the positioning accuracy of LBIE in three directions is 0.112 m,0.107 m,and 0.252 m,respectively,with improvements of 17.6%,27.2%,and 26.1%compared to GBIE,and 23.3%,28.2%,and 30.6%compared to ***,its computational time increases by 30–40%compared to ILS-PAR and is approximately half of that using TBIE.

关键词： Ambiguity resolution Best integer equivariant estimation Laplacian distribution Urban environments Low-cost GNSS receivers Real-time kinematic

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Initiation, Development and Stabilization of Cavities during Tensile Deformation of Semicrystalline Polymers

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Chinese Journal of Polymer Science 2018年第10期36卷 1195-1199页

作者： ying Lu Yong-feng Men State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China University of Science and Technology of China Hefei 230026 China

By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.

关键词： Cavitation Deformation Polymer Polubutene-1 Spherulite

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Does empowering women benefit poverty reduction?Evidence from a multi-component program in the Inner Mongolia Autonomous Region of China

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Journal of Integrative Agriculture 2021年第4期20卷 1092-1106页

作者： GU Rui NIE feng-ying Agricultural Information Institute Chinese Academy of Agricultural SciencesBeijing 100081P.R.China

Ending poverty is a top priority of the international development agenda,and governments worldwide have attached great importance to poverty alleviation ***,poverty reduction policies have mostly focused on men,which has widened the gap in productivity and income between men and women and increased gender *** paper aims to determine the impacts of a multi-component program on women's empowerment and poverty reduction,and explore the role empowered women play in poverty *** dataset used in this study was collected in nine poor counties of Ulanqab City in the Inner Mongolia Autonomous Region of China at the end of 2014,yielding a sample of 900 *** questions were used to reconstruct the baseline data and build a panel *** groups of rural households were further identified to better target the women in the beneficiary *** control the selection bias,propensity score matching,inverse probability weighting,and the difference-in-differences matching method were used to analyze the effect of the program and undertake robust *** results show that the program has positive effects on women's empowerment and poverty reduction *** women also has positive effects on poverty reduction,and the women who were the beneficiaries have contributed to increasing the incomes and living standards of ***,microfinance,and associations are common means or strategies to empower women to address *** paper provides new empirical evidence that women can benefit from a gender-focus program through portfolio intervention such as training,cooperatives,and *** women further improve the livelihoods of poor households and help lift them out of *** results suggest that researchers and policymakers need to pay more attention to poverty issues from the perspective of gender.

关键词： women empowerment poverty reduction Inner Mongolia Autonomous Region

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弹性网络正则化的高维序列因果关联识别研究

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华北理工大学学报（自然科学版） 2025年第1期47卷 96-105页

作者：张居营安风楼河北金融学院金融与投资学院河北保定071051 太平洋证券股份有限公司北京100033

弹性网络正则化方法兼顾了L1正则化与L2正则化的优点,能够解决高维时间序列因果关系分析中共线性、过度拟合与信息冗余等问题,有效发掘高维序列之间的主要关联关系。首先,基于VAR模型与长期格兰杰因果关联网络,阐述高维序列因果关联识... 详细信息

弹性网络正则化方法兼顾了L1正则化与L2正则化的优点,能够解决高维时间序列因果关系分析中共线性、过度拟合与信息冗余等问题,有效发掘高维序列之间的主要关联关系。首先,基于VAR模型与长期格兰杰因果关联网络,阐述高维序列因果关联识别的方法;其次,讨论了弹性网络正则化如何解决高维序列因果关系建模的弊端,融合L1与L2正则化的主要特点;最后,结合多维大宗商品期货价格日度波动率序列,探索了弹性网络正则化在高维序列因果关联识别的应用,并与其他正则化方法进行比较。结果表明,弹性网络正则化方法避免了信息冗余与“过度稀疏化”的问题,识别与提炼商品价格波动因果关联网络中的主要影响节点与传导关系,挖掘序列关系网络中的主要因果关联。

关键词：弹性网络正则化高维序列长期格兰杰因果关联网络

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Catalytic Oxidation of NO over La_(0.8)Sr_(0.2)MnO_3 Perovskite

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Chemical Research in Chinese Universities 2008年第5期24卷 620-627页

作者： zhAO ying-xian WEI feng YU ying Ningbo Institute of Technology zhejiang University Ningbo 315100 P. R. China

Catalytic oxidation of NO by O2 over La0.8Sr0.2MnO3 was tested in a tubular *** reaction temperature ranged from 373 to 473 K,space time from 0.090 to 0.720 s,inlet NO concentration from 300 to 2000μL/L, and O2 volume fraction from 3%to 9%.The steady-state conversion of NO was increased significantly with increasing reaction temperature and the space time,slightly with increasing the O2 concentration but decreased with increasing the inlet NO concentration at a lower *** the conditions of 0.720 s space time,500μL/L NO concentration, 5%O2 volume fraction and 473 K,NO conversion reached 90%.A kinetic model including a network of 12 elementary reactions with the desorption of NO2 as the rate-limiting step is established and fits the experimental data *** activation energy of NO2 desorption from the catalyst surface is determined to be 101 kJ/mol.

关键词： Catalytic oxidation Nitric oxide La0.8Sr0.2MnO3 catalyst Kinetics

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